Bridge-nesting peregrine falcon fledglings take a tumble but get helping hands toward survival

USFWS biologist Craig Koppie returns two rescued peregrine falcons to their nest atop the St. Georges BridgeST. GEORGES (June 18, 2013) – A winning combination of citizen awareness, DNREC Division of Fish & Wildlife Enforcement, Tri-State Bird Rescue & Research, and the US Fish & Wildlife Service collaborated recently to rescue and subsequently return a pair of juvenile peregrine falcons to their nesting location on the St. Georges Bridge over the Chesapeake & Delaware Canal after the birds had “crash-landed” on the bridge’s roadway while attempting their first flight.

Known as the world’s fastest bird, peregrine falcons have nested in Delaware since the late 1980s when they were carefully reintroduced to the eastern United States as the population rebounded from a federally endangered species listing. Due to the pesticide DDT, the entire eastern population had completely disappeared and recovery was uncertain. Delaware was not an obvious place for bringing them back, as the landscape lacks any naturally-occurring cliffs, the peregrines’ preferred habitat. However, the state boasts several large and high bridges that the falcons find as a surrogate for cliffs. The first nesting pair was on the Delaware Memorial Bridge, and over the past three decades, falcons have also taken up residence on the Summit, St. Georges, and Reedy Point Bridges over the C&D Canal. 

Three years ago, the Division of Fish & Wildlife began monitoring a new pair of peregrines atop the St. Georges Bridge. The steel truss bridge serves well as nesting location, or aerie, but it also can be a perilous place for juvenile falcons as they prepare to make their first flights. With their nest scrape high in the arches of the bridge, young birds have fallen into the C&D Canal or landed on the deck of the bridge, often resulting in mortality.The two rescued falcons are safely returned to the catwalk during a successful release atop the St. Georges Bridge.

Twice this month, two fledglings leaving the St. Georges Bridge nest for the first time might have met with such misfortune. Instead, quick thinking by citizens who saw and reported the falcons on the deck and roadbed of the bridge – amidst passing traffic – triggered a quick response from Division of Fish & Wildlife Enforcement agents who rescued the falcons and transported them to the nationally-renowned Tri-State Bird Rescue in Newark. 

After thorough examination and a few days of observation, Tri-State Bird Rescue reported that both falcons were in great condition and ready to be returned to their nest. On Wednesday, June 12, U.S. Fish and Wildlife Service raptor biologist Craig Koppie attempted to reintroduce the two juveniles, both females, to their parents.  

With the actual nest site a precarious perch inaccessible to humans, Mr. Koppie elected to place the falcons on the catwalk of the bridge, giving them a safer venue for continuing to exercise their wings and to make short flights. “Returning the young to the nest at this age is often difficult and requires a plan so the release will not end up in the same manner – with birds falling to the ground again,” he said. “To minimize risk of the birds immediately taking flight before they’re ready, I immersed the young falcons in water to soak their body and flight feathers. This makes the fledglings heavy and wet, and they will not have the desire to bolt once released. I also placed food (quail) along the catwalk before taking them to the top of the bridge so the young falcons would concentrate on eating while they were drying off.” 

As he scaled the bridge to release the juveniles, the adult falcons recognized their offspring from on high and became aggressive toward him; Mr. Koppie took this behavior as an excellent sign that the young birds were still being defended by their parents, and that the adults would continue to attend to their offspring’s needs. 

Thus, a successful release, and it seemed that all was well with the young falcons – with a little luck they would be airborne again in a day or two, this time for good. However, heavy thunderstorms were forecast over the next few days and strong winds could have dashed hopes for the falcons’ survival. Division of Fish & Wildlife biologist Anthony Gonzon was determined to monitor the birds in the storms’ aftermath. Arriving at St. Georges Bridge in the early morning Friday, June 14, he immediately located one of the adult peregrines on the catwalk beneath the bridge. Panning across the arches, he spotted one of the juveniles, a poignant sighting, Mr. Gonzon recalled: “At the very least, one of the young birds had survived the storms, and better yet, it could fly!” 

Gonzon spent more time combing the horizon for the second juvenile rescue. During that time, the other adult falcon flew in with food for the first juvenile and tried to coax it off the crossbeam of the arch where it was first observed. The young bird made a couple of attempts to take flight, but elected to stay put and wait for the adult to deliver its food. When the adult landed, the young falcon quickly ran to it, stole the carcass of a bird away and made a fast break for cover. 

“But there was still no sign of the second juvenile,” Mr. Gonzon recalled. Time and circumstances conspired against a sighting when, suddenly, on the north bank of the canal, he saw both adult falcons, clearly agitated and diving at some unseen threat. “A quick look through a spotting scope and there it was – the second peregrine fledgling! The parents obviously had been protecting her. Although she still had a little down on her head, she could fly, and fly well enough to perch on a dead tree along the canal.” The peregrine parents successfully drove off whatever threat they had detected, and the young bird flew back to the catwalk under the bridge, capping a restoration success. And evidence, according to Mr. Gonzon, “that Delaware’s peregrine falcon population had grown by two!” 

“We work hard to reunite young birds of prey with their parents or a foster family whenever we can,” said Lisa Smith, executive director of Tri-State Bird Rescue & Research. “Young birds of prey have so much to learn from the adults – how to hunt, how to behave socially, where to roost, etc. We are delighted that these two falcons can continue to grow up in the wild.”

Photo credits: Top, Russ Carlson. Bottom: USFWS/Craig Koppie.

Contact: Michael Globetti, DNREC Public Affairs, 302-739-9902

Vol. 43, No. 250